In electrical apparatus and products, a plurality of fuses are used to protect various electrical loads. One such application is telephone switching systems. There, a source of current is supplied to the plurality of fuses and their respective loads via a bus bar. The bus bar is a longitudinal strip or bar of conductive material having a plurality of spaced-apart tapped holes to receive respective screws. Each screw clamps a "spade" head terminal to the bus bar, the "spade" head terminal being received between the bus bar and a washer carried by the screw. The "spade" head terminal, in turn, is crimped to one end of a jumper wire. The other end of the jumper wire is crimped to a tab on the fuse (such as a "FASTON" tab connector available from AMP Incorporated of Harrisburg, Pa., U.S.A.).
Thus, each fuse has its own jumper and "spade" head terminal, and the system requires extensive wiring and precise connections between tabs and jumpers. The location on the longitudinal bus bar from which a tabbed fuse device is supplied current thereto is called a "tap," and the distance between taps is called the "pitch" or "tap pitch".
Problems occur in the known switching systems because each individual tab must be connected to an individual jumper and, in turn, to a particular location on the bus bar. Such a limitation is time consuming, labor intensive, inefficient, complicates assembly and repair, and increases manufacturing costs. Additionally, the numerous interfaces reduce reliability, and the extensive wiring causes resistance and heating. Further disadvantages of a structural nature are found in the known connectors, including requiring excessive space, and sacrificing economy of construction to achieve structural integrity.
On the other hand, and for completely different purposes, louvered spring devices have been used. For example, U.S. Pat. No. 3,453,587 (issued to Neidecker on Jul. 1, 1969) discloses use of a louvered spring bent into a substantially circular form and used for lining the interior of a confined plug space into which an exactly matable plug is inserted. Further, U.S. Pat. No. 3,845,451 (issued to Neidecker on Oct. 29, 1974) discloses exactly matable jack and plug units plugged together; the interior of the jack has a metal plate cut with a plurality of tongues which are twisted out of the plane of the metal plate so that they extend into the interior of the jack and bear on the respective jack inserted into the plug. Also, U.S. Pat. No. 4,013,329 (issued to Hugin on Mar. 22, 1977) discloses stacks of plates having spring-loaded fins to improve the quality of the electrical connection between opposing solid plates and to eliminate the need for high-pressure contact between opposing plates in heavy-duty connector equipment.
Louvered strips are commercially available, such as "Louvertac" strips available from AMP Incorporated of Harrisburg, Pa., U.S.A. The strips may be cut into various lengths and, since the product applications are circular or concentric, the strips are bent into circular forms.
Nevertheless, for many years a need has existed for a simple, efficient low-cost means for connecting fuses to a bus bar in a switching system.
This means should provide assured electrical connections along the length of the bus bar sufficient to transmit substantial levels of current.